Electrode apparatus for preventing cracking of the electrode and insulating layers

Abstract

It is an object of the invention to prevent not only cracking but also blocking of an electrode layer 20 and an electrically insulating layer 30, particularly the electrically insulating layer 30, which is formed on a base film 10. An electrode apparatus comprises a base film 10 for defining a recess 50 at the inner periphery of a bending part 500, and an electrode layer 20 and an electrically insulating layer 30 which are pattern formed on the base film 10. The electrode layer 20 crosses the bending part 500 from the inside of the recess 50 to the outside. The electrically insulating layer 30 covers the upper part of the electrode layer 20 in the vicinity of the bending part 500. A resin composition obtained by admixing a low Tg resin having a glass transition temperature equal to 25 degrees C. or lower and a high Tg resin having a higher glass transition temperature (for example, 40 degrees C. or higher) than that of the low Tg resin is used as a dielectric of the electrically insulating layer 30.

Description

[0001]This application claims priority benefits from Japanese Patent Application No. 2002-249858 filed Aug. 29, 2002.FIELD OF THE INVENTION[0002]This invention relates to an electrode apparatus for biocompatible electrode apparatus which can be used in the medical field such as treatment and diagnosis of illness, and more particularly to an electrode apparatus which can prevent the occurrence of cracking of an electrode layer and an electrically insulating layer which are elements composing the electrode apparatus.BACKGROUND OF THE INVENTION[0003]The iontophoresis (Acta Dermatol venereol, vol. 64, p. 93, 1984) and the electropolation (National Patent Publication No. H03-502416, Proc. Acad. Sci. USA, vol. 90, p. 10504 through 10508, 1993) teach a treatment method in which chemicals and physiologically active substance are introduced into a living body from the skin and the mucous membrane by using electric energy. There is also known a method, in which a substance to be diagnosed is ...

AI Technical Summary

Benefits of technology

[0008]It is, therefore, an object of the present invention to provide a technique capable of preventing the occurrence of cracking of an electrode layer and an electrically insulating layer, particularly the electrically insulating layer formed on a base film, and also capable of preventing the occurrence of blocking.Means for Solving the Problem and Preferred Mode of the Invention

[0009]This invention is based on such finding that when two kinds of resins having a different glass transition temperature are blended (mixed), the blended resin composition has such characteristics as to independently show the respective glass transition temperatures of the two kinds of blended resins. By using a resin material having a glass transition temperature equal to 25 degrees C. or lower, preferably 0 degrees or lower, and more preferably −20 degrees or lower as in the preceding proposal, the electrically insulating layer is increased in flexibility, so that the occurrence of cracking can be prevented. Moreover, by using a resin material having a glass transition temperature equal to room temperature or higher, and preferably 40 degrees C. or higher as a dielectric which constitutes the electrically insulating layer, the occurrence of blocking can be prevented effectively. So, in the present invention, based on the above-mentioned finding, a resin composition which includes, at least, a low Tg resin having a glass transition temperature equal to or lower than 25 degrees C., and a high Tg resin having a higher glass transition temperature than that of the low Tg resin is used as a dielectric which constitutes the electrically insulating layer. The expression “which includes, at least,” refers to the inclusion of, in addition to resin, a solvent for dissolving the resin, and the known additives such as silica and bentonite. Moreover, it also means that other resins can be admixed in view of cost reduction and excellent suitability for coating. Other resins can be admixed in a small amount, for example, 3 wt. % or less, within a range not prejudiciary to the object of the present invention.

[0012]The electrode apparatus having a bending part is obtained by forming an electrode layer on one surface of the base film, and then forming an electrically insulating layer in such a manner as to cover at least a part of the electrode layer, then forming a bending part (normally, a dent or recess is defined such that its inner periphery serves as a receptacle part) by cold pressing in order to avoid the occurrence of thermal breaking of the electrode layer and the electrically insulating layer and thereafter punch-working the base film into a predetermined shape. Therefore, the electrode apparatus having a bending part generally includes a first part (dent) having a small height and a second part (electrode terminal part) having a large height part with the bending part disposed therebetween. In order to form an electrode layer and an electrically insulating layer on the base film, printing such as screen printing and gravia is suitably applied. Particularly, by applying the screen printing, the thickness can easily be controlled and in addition, a pattern can correctly be drawn by printing. As a material of the electrode layer, various kinds of electrode materials can be applied. In case the electrode layer is formed by printing, for example, paste ink (particularly, one which is readily elongated such as ink chiefly composed of carbon and readily elongated) can be used. Since the electrically insulating layer is provided in such a manner as to prevent the electrode part from directly contacting the skin, it covers the electrode layer in such a manner as to necessarily include the bending part. Accordingly, the thickness of the electrically insulating layer should be set to, for example, 0.5 μm through 100 μm and more preferably to 1 μm through 30 μm, so that effective electrically insulating properties can be maintained considering the elongation due to the pressing.

Problems solved by technology

A serious technical problem involved in the electrode apparatus having a bending part of the type mentioned above is to effectively prevent the occurrence of cracking of the electrode layer and the electrically insulating layer which readily occurs in the vicinity of the bending part.

Cracking of the electrode layer is liable to cause an electric cut-off, and cracking of the electrically insulating layer is liable to expose the electrode layer, thus resulting in leakage of electricity.

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